Healthcare associated infections (HAI) are a major source of morbidity and mortality despite the fact that they are often preventable. Most HAI are associated with an invasive device and disproportionately occur in elderly patients admitted to intensive care units (ICU). The annual cost of HAI to hospitals has been estimated to be $6.5 billion. While effects of HAI are likely to extend well beyond hospital discharge, especially in the elderly, there has been little study of the long term health or economic outcomes attributable to HAI. Over 30 years ago, using a survey and medical record reviews, the Centers for Disease Control and Prevention (CDC) conducted a seminal national study in which level of infection control staffing and intensity of infection prevention, surveillance, and control (IPSC) interventions were linked to HAI rates. However, this study has not been updated. While a number of current guidelines exist, recommendations are inconsistent and poorly followed. Despite rising HAI rates and the need to assess the impact of current IPSC processes, there is a gap in the knowledge regarding both their clinical effectiveness and cost-effectiveness. The aims are to: 1) Describe the level of infection control staffing and intensity of IPSC interventions currently in place in ICU across the nation;2) Determine associations between current infection control staffing and intensity of IPSC interventions, and probability HAI and short term survival in elderly ICU patients;3) Estimate the long term outcomes attributable to HAI in elderly patients;and 4) Determine the cost-effectiveness of effective infection control staffing and IPSC interventions in ICU. We have revised the survey used in the CDC study to reflect current IPSC processes (i.e., staffing and ten IPSC interventions). The new survey was pilot tested and found to be reliable and valid. To meet Aim 1, we propose to use this survey during Phase I of data collection in a sample of infection control professionals who participate in the CDC's National Healthcare Safety Network (NHSN) to determine current IPSC processes. To meet Aim 2, in Phase II of data collection, we will randomly select a stratified sub-sample from Phase I respondents and obtain standardized HAI data, administrative data in 83 ICU, and Medicare files for elderly patients (n ~ 80,000). For Aim 3, we will build upon a previous study (R01HS11978) and follow a cohort of elderly patients (n = 39,314) identified with and without HAI using the NHSN protocols. We will follow this cohort using 5-years of Medicare data. All data will be used for Aim 4. The analytic strategies proposed include multivariate econometric methods designed to minimize potential bias and address clustering of data. Results will inform the practice of infection control professionals and bedside clinicians, allowing them to base their practices on current evidence, which should improve patient outcomes and reduce HAI rates.